Using nine ravens, researchers taught the birds to trade a small crust of bread for a more tasty piece of cheese. In the first "fair" phase of the experiment, a trainer at one end of a cage gave a bird a piece of bread crust, which it carried in its mouth to the opposite end of the cage–where it was offered to a second researcher's outstretched hand in exchange for cheese.

In the second "unfair" phase of the experiment, the raven followed the same procedure, but the trainer then ate the morsel of cheese instead of exchanging with the raven.

After two days, the procedure was set up with the "fair" trainer, the "unfair" trainer, and a third neutral trainer. Of seven birds tested, six chose the fair trainer and one chose the neutral trainer. After a month, all nine were tested, during which seven chose the fair trainer, one chose the unfair trainer, and the last chose the neutral trainer.